I felt disturbed... Especially when he was blasting objects while drunk with a high powered weapon into a crowd of civilians.... Would it have been more scary if instead of a blast he was holding a gun?

Much scarier. I don't think of IM's computer targeted light show that has never ever hurt any civilians the same way I do an indiscriminate pistol that has a long history of being used on innocents.

If he had missed any of the fast moving targets while being stupid-drunk, perhaps it would have entered my mind that he could have missed any more than when he sniped the hostage holders in that village in IM1. But as is, Tony didn't think he'd miss, and he didn't have any trouble at all, he was just abusing his power. Rhodey didn't even bother to clear the room until there was a fight. I don't think the scene painted the crowd as in any real danger. They didn't even get a safe distance from the house during a superhero fight.